User-friendly temporal queries on historical knowledge bases

DBpedia and other RFD-encoded Knowledge Bases (KB)s give users access to encyclopedic knowledge via SPARQL queries. As the world evolves, the KBs are updated, and the history of entities and their properties becomes of great interest. Thus, we need powerful tools and friendly interfaces to query histories and flash-back to the past. Here, we propose (i) a point-based temporal extension of SPARQL, called SPARQLT, which enables simple and concise expression of temporal queries, and (ii) an extension of Wikipedia Infoboxes to support user-friendly by-example temporal queries implemented by mapping them into SPARQLT. Our main-memory RDF-TX system supports such queries efficiently using Multi-Version B+ trees, compressed indexes, and query optimization techniques, which achieve performance and scalability, as demonstrated by experiments on historical datasets including Cliopedia derived from Wikipedia dumps. We finally discuss how provenance information can be used to add valid-time features to these transaction-time KBs.